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131 lines
3.7 KiB
131 lines
3.7 KiB
/****************************************************************************
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**
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** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
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** All rights reserved.
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** Contact: Nokia Corporation (qt-info@nokia.com)
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**
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** This file is part of the QtCore module of the Qt Toolkit.
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**
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** $QT_BEGIN_LICENSE:LGPL$
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** Commercial Usage
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** Licensees holding valid Qt Commercial licenses may use this file in
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** accordance with the Qt Commercial License Agreement provided with the
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** Software or, alternatively, in accordance with the terms contained in
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** a written agreement between you and Nokia.
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**
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** GNU Lesser General Public License Usage
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** Alternatively, this file may be used under the terms of the GNU Lesser
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** General Public License version 2.1 as published by the Free Software
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** Foundation and appearing in the file LICENSE.LGPL included in the
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** packaging of this file. Please review the following information to
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** ensure the GNU Lesser General Public License version 2.1 requirements
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** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
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**
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** In addition, as a special exception, Nokia gives you certain additional
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** rights. These rights are described in the Nokia Qt LGPL Exception
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** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
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**
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** GNU General Public License Usage
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** Alternatively, this file may be used under the terms of the GNU
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** General Public License version 3.0 as published by the Free Software
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** Foundation and appearing in the file LICENSE.GPL included in the
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** packaging of this file. Please review the following information to
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** ensure the GNU General Public License version 3.0 requirements will be
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** met: http://www.gnu.org/copyleft/gpl.html.
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**
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** If you have questions regarding the use of this file, please contact
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** Nokia at qt-info@nokia.com.
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** $QT_END_LICENSE$
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**
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****************************************************************************/
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#ifndef QTCONCURRENT_MEDIAN_H
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#define QTCONCURRENT_MEDIAN_H
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#include <QtCore/qglobal.h>
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#ifndef QT_NO_CONCURRENT
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#include <QtCore/qvector.h>
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#include <QtCore/qalgorithms.h>
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QT_BEGIN_HEADER
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QT_BEGIN_NAMESPACE
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QT_MODULE(Core)
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#ifndef qdoc
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namespace QtConcurrent {
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template <typename T>
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class Median
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{
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public:
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Median(int _bufferSize)
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: currentMedian(), bufferSize(_bufferSize), currentIndex(0), valid(false), dirty(true)
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{
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values.resize(bufferSize);
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}
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void reset()
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{
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values.fill(0);
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currentIndex = 0;
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valid = false;
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dirty = true;
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}
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void addValue(T value)
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{
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currentIndex = ((currentIndex + 1) % bufferSize);
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if (valid == false && currentIndex % bufferSize == 0)
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valid = true;
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// Only update the cached median value when we have to, that
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// is when the new value is on then other side of the median
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// compared to the current value at the index.
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const T currentIndexValue = values[currentIndex];
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if ((currentIndexValue > currentMedian && currentMedian > value)
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|| (currentMedian > currentIndexValue && value > currentMedian)) {
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dirty = true;
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}
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values[currentIndex] = value;
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}
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bool isMedianValid() const
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{
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return valid;
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}
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T median()
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{
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if (dirty) {
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dirty = false;
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QVector<T> sorted = values;
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qSort(sorted);
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currentMedian = sorted.at(bufferSize / 2 + 1);
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}
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return currentMedian;
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}
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private:
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QVector<T> values;
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T currentMedian;
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int bufferSize;
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int currentIndex;
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bool valid;
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bool dirty;
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};
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} // namespace QtConcurrent
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#endif //qdoc
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QT_END_NAMESPACE
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QT_END_HEADER
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#endif // QT_NO_CONCURRENT
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#endif
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